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RE: [Bug 7796] New: Misleading statement on change to unions

From: Michael Kay <mike@saxonica.com>
Date: Sat, 3 Oct 2009 10:44:16 +0100
To: "'C. M. Sperberg-McQueen'" <cmsmcq@blackmesatech.com>, <www-xml-schema-comments@w3.org>
Cc: "'Kevin Braun'" <kbraun@obj-sys.com>
Message-ID: <53E630ABF0A342608436EA02BAE7F25F@Sealion>
> I believe (without spending more time than I already have, 
> checking the decision record) that the change was made to 
> resolve bugs 2044 and 2333, which relate to the unintentional 
> loss of union-level facets when xsi:type is used to select a 
> particular member type.  But speaking for myself, I think 
> that XSD 1.1 gains in simplicity by eliminating 1.0's ad hoc 
> prohibition on unions as member types of unions, so that I 
> would have favored the change in any case.  The specific bug 
> relating to lost union facets is just one example of the way 
> fate punishes non-orthogonal designs. 

It's worth noting that we've recently identified a problem in the
XSLT/XQuery type system which has essentially the same root cause, and which
is unrelated to xsi:type.


Michael Kay
Received on Saturday, 3 October 2009 09:44:50 UTC

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